Chapter one introduces the notion of self reference and the role of handwriting in self referential processing. The self-reference effect reveals the capacity of people to encode information related to the self, independently by which level the self is implicated in the information (Rogers, 1977). The following chapters report experimental evidence that handwriting is a specific domain for the study of the self. Several experiments are described, based on discrimination and identification tasks.
Chapter two reports the first experiment, a pilot study that evaluates a possible specificity of self-related processing in discrimination tasks involving handwriting. In this experiment I used an implicit task, under the hypothesis that the discrimination between two handwritings is simpler when one of them is the own handwriting, rather than when both are others’ handwritings. My results support this hypothesis and are in line with those by Chen et al. (2008), who found that the perception of own handwriting is special and related to the self, which implies that implicit self–related processing could be elicited by handwriting stimuli.
Chapter three reports the second experiment, on children of 3rd and 5th grade (about 8 and 10 year old, respectively). The aim of this study was to investigate the self reference effect and how the sense of ownership developes in children. Furthermore, I considered the relation of friendship to control for the familiarity of handwriting. Participants were pairs of best friends. I hypothesized that in children the discrimination between own, best friend and other handwritings was different between the two groups of children. I found that 3rd grade children manifest only a familiarity effect because they were able to discriminate between self/friend and other but not between self and friend. This ability grows up in 5th grade children where I found a familiarity effect and self reference effect. This was in line with friendship (Rawlins, 1992) and handwriting (Ehri and McCormick, 2004) development.
Chapter four reports the third experiment, conducted in collaboration with Professor Erik Chang of the Institute of Cognitive Neuroscience of the National Central University, Taiwan. It was focused on the recognition and identification of handwriting dynamic traces. In this study I tried to explain if the action related knowledge contributes to recognize one’s own past action (Knoblich and Flach, 2003). Participants responded to their own and other kinematic traces in a lexical decision task and an identification task included in a fMRI session. The lexical decision task revealed a significant effect of authorship and higher sensitivity for forward than backward traces. The fMRI experiment indicated that viewing traces elicited bilateral medial frontal, parietal, insula, ventral parietal activations and right superior frontal gyrus and temporal gyrus. These activations were in line with the literature. temporal gyrus and parietal lobule were implicated in central processes for writing Chinese characters (Lin et al., 2007). Activations in the left parietal lobule, the right superior temporal gyrus and left middle frontal gyrus were implicated in Chinese orthographic, phonological, and semantic processing. I found also activation in the visuospatial processing areas (SOG/SPL), visual pattern memory (MTG), and motor areas (MFG/SMG). These areas need to work synchronously for a relative long period, especially for unfamiliar character’s traces. My results are in line with biological motion perception, that involves activation in temporo-parietal-occipital junction (Peelen et al., 2006, Peuskens et al., 2005).
In chapter five I described the fourth experiment, aimed at studying the effects of participant’s gender and grammatical gender of the word whose handwriting should be classified on the classification of writer’s gender. The only specific hypothesis was referred to the own sex bias, according to which participants’ responses in a yes/no task are biased towards the same-sex response. In other respects the study was exploratory, in the sense that no specific hypotheses were formulated in advance. Results showed two effects: the participant’s responses were biased by both the gender of word and the gender of handwriting, in agreement with Cellerino et al. (2004).
Chapter six includes the general discussion of results obtained in the four experiments. Results confirmed that it is possible investigate self process with handwriting because it allows to explore different aspects of self. Handwriting points out self reference effects: self superiority in discrimination and identification, including also information about familiarity and authorship.